Expression of mRNA and proteins for testicular steroidogenic enzymes and brain and pituitary mRNA for glutamate receptors in rats exposed to immobilization stress

The objectives of this study were to determine whether stress attenuates th e pituitary LH response to excitatory amino acids by altering expression of glutamate receptor I (GluR1) and N-methyl-D-aspartic acid (NMDA) receptor mRNA levels in the hypothalamus or pituitary, and assess whether stress inf luences testicular levels of mRNA or protein for steroidogenic enzymes. Thr ee hours (h) of immobilization stress was associated with a greater than 7- fold increase in serum corticosterone, and a marked reduction in serum test osterone (T) concentrations. Stress did not significantly alter hypothalami c or pituitary GluR1 and NMDA receptor mRNA levels. Although transcript lev els for P450(SCC) and P450(17 alpha) mRNA in the testis were unchanged in s tressed rats, western blotting of testicular fractions revealed reduced amo unts of P450(SCC) and 3 beta-HSD, but not P450(17 alpha). The data suggest that immobilization stress reduces T production by suppressing the translat ion of transcripts for P450(SCC) and 3 beta-HSD, but the attenuated LH resp onse of stressed animals to NMDA is not mediated by altered hypothalamic or pituitary expression of GluR1 and NMDA receptor levels. (C) 1999 Elsevier Science Ltd. All rights reserved.